Bolt fastening force ultrasonic detection and key detection parameter determination method based on finite elements

Abstract

The invention provides a bolt fastening force ultrasonic detection and key detection parameter determination method based on finite elements. The method is suitable for bolting force ultrasonic soundtime nondestructive measurement. The finite element theory and the acoustic elasticity principle are combined, and a bolt fastening force ultrasonic detection principle model is established. A bolt finite element model and a static simulation are established, the bolt axial stress distribution rule on the ultrasonic propagation path is obtained, so that the shape factor of the bolt is determined.The ultrasonic detection coefficient of the bolt fastening force is calculated by combining the acoustic elasticity coefficient of the bolt material measured by the critical refraction longitudinal wave. The method is low in cost and good in adaptability, and the detection coefficient can be accurately and quickly determined.

Description

1. Technical field [0001] The invention relates to the technical field of bolt fastener detection, and proposes a finite element-based ultrasonic detection of bolt fastening force and a method for determining key detection parameters. The method is suitable for nondestructive measurement of bolt fastening force by ultrasonic acoustic time method. 2. Background technology [0002] Bolted connections are widely used in industrial fields such as armored vehicles, aerospace, and special machinery because of their advantages such as simple assembly, convenient disassembly, high efficiency, low cost, and good adaptability. For different types of bolts, in order to ensure the working quality and reliability of mechanical equipment, a certain pre-tightening force must be given to the bolts. Bolts with too large pre-tightening force are prone to breakage under the action of axial load. The required clamping effect cannot be achieved, so accurately controlling the magnitude of the pre...

AI Technical Summary

Problems solved by technology

Among them, the resistance strain gauge method and the photomechanical method are rarely used in engineering due to the limitation of the detection principle and measurement conditions; the torque wrench method is currently the most commonly used bolt pretightening force control and measurement method in engineering, but due to the bolt and The discretization of the friction coefficient between the threaded surface of the nut and the contact surface between the nut and the connected part leads to the discretization of the torque coefficient. In practical applications, there will also be a large error, up to about 30%.

The key and premise of the ultrasonic measurement method is to obtain the accurate mathematical relationship between the ultrasonic propagation time and the fastening force, that is, the measurement coefficient. The general method is to obtain the measurement coefficient under different specifications of bolts and connection states through a large number of experiments. This method is expensive. , poor adaptability, which is not conducive to the engineering application of the bolt tightening force ultrasonic testing method

Images